Despite profound advances in the understanding the biology of cancer, the treatment of the most common cancers of adults, such as those of the breast, prostate, lung, colon, ovaries, etc., remains far from satisfactory. Without a doubt, there have been major advances; equally without a doubt, a very large medical need remains unmet. Successful treatment of any disease requires a clear understanding of that which is unique about the disease, followed by finding a way to attack the disease at the point of its uniqueness. This principle has been the basis of all major successes in medicine.
Cancers, in contrast to bacterial infections, for example, are not foreign entities; they are derived from our own self. Because of the overwhelming commonality between cancers and our healthy tissues, cancer has been approached by trying to find biological pathways which the cancers use, and which our normal bodies use less, i.e., to aim for selectivity as opposed to specificity. This approach, illustrated by chemotherapy, is the major nonsurgical approach to cancer therapy today. It is somewhat effective, but since the efficacy is not based on specificity but on selectivity, chemotherapy attacks the normal tissues as well, leading to the well-known side effects of the treatment, which also limit its use.
Recent years have seen increasingly sophisticated tools of chemotherapy, but the fundamental problem that chemotherapy is not specific to cancer but only selective for it remains, and thus it has been for several decades.
An exception that proves the rule is imatinib, a treatment for a common adult leukemia. This kind of leukemia, chronic myelogenous leukemia or CML, results from a very specific change in the blood cells. The change is known and it is also known that the change is only in the leukemia cells. The drug imatinib specifically targets this change and is enormously effective against CML. Unfortunately, CML remains a rather unique example where the specificity can be and has been defined; fortunately, it is also a prime example of the fact that the definition of specificity can lead to highly effective cancer therapy.
What is needed are methods of determining the basis of cancer specificity and then applying this specificity to develop successful, non-toxic therapies.